Near net shape additive manufacturing

ABSTRACT

An additive manufacturing apparatus includes a first vertically-extending support leg, a second vertically-extending support leg, and a gantry supported on the first and second support legs. The additive manufacturing apparatus also includes a work table movably supported beneath the gantry, a print head supported on the gantry, and a trim head supported on the gantry with the print head.

TECHNICAL FIELD

Aspects of the present disclosure relate to apparatus and methods forfabricating components. In some instances, aspects of the presentdisclosure relate to apparatus and methods for fabricating components(such as, e.g., automobile parts, medical devices, machine components,consumer products, etc.) via additive manufacturing techniques orprocesses, such as, e.g., 3D printing manufacturing techniques orprocesses.

BACKGROUND

Additive manufacturing techniques and processes generally involve thebuildup of one or more materials to make a net or near net shape (NNS)object, in contrast to subtractive manufacturing methods. Though“additive manufacturing” is an industry standard term (ASTM F2792),additive manufacturing encompasses various manufacturing and prototypingtechniques known under a variety of names, including e.g., freeformfabrication, 3D printing, rapid prototyping/tooling, etc. Additivemanufacturing techniques may be used to fabricate simple or complexcomponents from a wide variety of materials. For example, a freestandingobject can be fabricated from a computer-aided design (CAD) model.

A particular type of additive manufacturing is commonly known as 3Dprinting. One such process, commonly referred to as Fused DepositionModeling (FDM) or Fused Layer Modeling (FLM) comprises a process ofmelting a thin layer of thermoplastic material, and applying thismaterial in layers to produce a final part. This is commonlyaccomplished by passing a continuous thin filament of thermoplasticmaterial through a heated nozzle, which melts the material and appliesit to the structure being printed. The heated material may be applied tothe existing structure in thin layers, melting and fusing with theexisting material to produce a solid finished product.

The filament used in the aforementioned process may be produced by, forexample, using a plastic extruder, which may include a steel extruderscrew configured to rotate inside of a heated steel barrel.Thermoplastic material, in the form of small pellets, may be introducedinto one end of the rotating screw. Friction from the rotating screw,combined with heat from the barrel, may soften the plastic, which maythen be forced under pressure through a small round opening in a diethat is attached to an end of the extruder barrel. This may extrude astring of material which is cooled and coiled up for use in the 3Dprinter.

Melting a thin filament of material in order to 3D print an item may bea slow process, which may be suitable for producing relatively smallitems or a limited number of items. Therefore, the melted filamentapproach to 3D printing may be too slow to manufacture large items.However, the fundamental process of 3D printing using moltenthermoplastic materials may offer advantages for the manufacture oflarger parts or a larger number of items.

In some instances, the process of 3D-printing a part may involve atwo-step process. For example, the process may utilize a large printbead to achieve an accurate final size and shape. This two-step process,commonly referred to as near net shape, may begin by printing a part toa size slightly larger than needed, then machining (e.g., by milling orrouting), the part to the final size and shape. The additional timerequired to trim the part to its final size may be compensated for bythe faster printing process.

Print heads for additive manufacturing machines used to printthermoplastic material in relatively large beads have generally includeda vertically-mounted plastic extruder connected to a print nozzle todeposit the bead of material onto a surface and/or part being printed.The flowable material, such as, e.g., molten thermoplastic material, maybe infused with a reinforcing material (e.g., strands of fiber) toenhance the material's strength. The flowable material, while generallyhot and pliable, may be deposited upon a substrate (e.g., a mold), andthen pressed down or otherwise flattened and/or leveled to a consistentthickness. Traditional print heads may include an oscillating platesurrounding the nozzle, the plate being configured to oscillatevertically to flatten the bead of material against the surface or parton which the bead is deposited, which may include a previously-depositedbead of material. The deposition process may be repeated so that eachsuccessive layer of flowable material is deposited upon an existinglayer to build up and manufacture a desired structure for a component orpart. In order to achieve proper bonding between printed layers, it maybe necessary to ensure that the temperature of the layer being printedupon is within a certain range when a layer is deposited thereon. Forexample, the previously-deposited layer may need to have cooled to anappropriate degree and thereby solidified sufficiently to support thenew layer. However, this previously-deposited layer may need to retainsufficient heat to soften and fuse with the new layer, thus producing asolid part at the conclusion of the manufacturing process.

In near net shape additive manufacturing or 3D printing, the desiredpart may be printed in a series of layers. These layers may be slightlylarger than the desired size of the finished part. After these layerscool and harden, the part may be trimmed to the desired final size andshape. This approach may provide the advantage of being able to printusing relatively large print beads at relatively high speed, andmachining or trimming the printed part to the final size and shape. Thismay be significantly faster than printing with a print bead fine enoughto achieve the final size and shape using only the print process.

Near net shape additive manufacturing may involve two processes, aprinting process and a trimming process. Conventionally, these twoprocesses may be performed on separate machines in different locations.However, it may be desirable to perform these two separate process on asingle machine. In order to perform these processes on a single machine,two gantries may be included on such machine, one for printing and onefor trimming. While providing separate gantries may be suitable forrelatively large machines, such as machines having a footprint orprinting area of, for example, at least 10 feet by 20 feet, theinclusion of separate printing and trimming devices may introducesignificant costs. Additionally, the inclusion of separate gantries mayincrease the size of the machine and may be less suitable for smallermachines, such as machines that have a foot print or printing area ofabout 10 feet by 10 feet.

SUMMARY

Aspects of the present disclosure relate to, among other things, methodsand apparatus for fabricating components via additive manufacturing or3D printing techniques. Each of the aspects disclosed herein may includeone or more of the features described in connection with any of theother disclosed aspects. An exemplary aspect of this disclosure is amachine configured to perform both printing and trimming operations,which may be produced at a reduced cost. The exemplary machine may havea size that is smaller than other dual-gantry machines and therefore mayrequire less space.

In one aspect, an additive manufacturing apparatus may include a firstvertically-extending support leg, a second vertically-extending supportleg, and a gantry supported on the first and second support legs. Theadditive manufacturing apparatus may also include a work table movablysupported beneath the gantry, a print head supported on the gantry, anda trim head supported on the gantry with the print head.

In another aspect, an additive manufacturing apparatus may include afixed gantry, a print head support on the gantry, and a trim headsupport on the gantry with the print head. The additive manufacturingapparatus may include a vertical work table including a side surfaceconfigured to receive a bead of thermoplastic material extruded from theprint head and a support member extending below the side surface of thevertical work table to support a part.

In another aspect, an additive manufacturing method may includedepositing a first layer of thermoplastic material on a surface with aprint head supported on a gantry, and moving the surface with thedeposited thermoplastic material away from the print head. The additivemanufacturing method may also include depositing one or more additionallayers of thermoplastic material on the first layer of thermoplasticmaterial, and supporting at least a portion of the first layer or one ormore additional layers of thermoplastic material on a support member.

In yet another aspect, a machine may include a gantry (extending along ay-axis) mounted above a horizontal-moving print surface or work table.Once installed or assembled, the gantry may be fixed in position (e.g.,the gantry does not include a motor, such as a servomotor, to move thegantry with respect to the work table). For example, while the gantrymay be fixed, the work table may be movable in forward and backwarddirections (along an x-axis) with respect to the gantry. Two separatevertically-movable (along a z-axis) heads may be mounted on the gantry.A first one of these vertically-movable heads may be a print head fordepositing material to manufacture or print a part, while the othervertically-movable head may be a trim head for removing material fromthe part manufactured by the print head. The gantry may be sized suchthat the gantry may include portions that extend to opposite sides ofthe work table, and beyond respective sides of the work table. Thus, thegantry may provide coverage of the entirety of the work table.

In an exemplary arrangement, the print head and the trim head may beconnected to each other for moving back and forth along the gantry as aunit. Alternatively, the trim head may be moveable independent of theprint head such that, during printing, the trim head may be parked orstowed in a position spaced away from a part printed on the table. Insuch a configuration, once the part has cooled and solidified to anapproximately solid state, the print head may be moved upward and parkedor stowed. The parking location of the print and trim heads may be offthe table (e.g., to a side of the table). Thus, during printing of apart, the trim head may be moved completely off (to a side of) the tableand parked while the part is printed, and during trimming, the printhead may instead be parked. In configurations where the print and trimheads are connected and move as a unit, a parking location may insteadbe a raised position with respect to the z-axis such that the parkedhead is positioned above the active head. When the part cools, the trimhead may be lowered and drawn towards the printed part in order to trimthe part. Thus, the part may be trimmed using the trim head while theprint head is parked. In such a configuration, the print head and trimhead may operate independently while moving as a unit with respect tothe gantry. Whether connected or provided as separate components, theprint and trim heads may be supported on a single gantry, and maythereby produce a part as large as the table with a height that islimited only by the vertical stroke of the print head, due at least inpart to the movable work table.

In one aspect, it may be desirable to produce a relatively smaller parthaving a height greater than the vertical (z-direction) stroke of theprint head. In these instances, the machine may be reconfigured to printvertically rather than horizontally. For example, the machine mayinclude at least one print nozzle which, when installed on the machinemay allow material to flow (and be deposited) horizontally, rather thanvertically. A second, vertically-extending, table having a heightapproximately equal to the vertical stroke of the print head, may bemounted vertically to the back of the moving horizontal table tofacilitate horizontal deposition of material (e.g., on avertically-extending surface) for vertical printing.

The vertical table may be moveable with respect to the print head. Thepart may be vertically-printed on the vertical table with this tablepositioned adjacent to the print head. As each layer is printed, coupledhorizontal and vertical tables may together move away from the printhead by the distance required to print the next layer or bead.

In at least some configurations, the horizontally-extending print nozzlemay not deposit material at a surface of the horizontal table wheninstead depositing material on the vertical work table. Thus, during themanufacturing process, the part manufactured may be suspended on thevertical work table above the horizontal table. In one aspect, adistance between the horizontal table and the suspended part mayinitially be equal to a distance to ensure the print head has sufficientclearance above the horizontal work table during manufacturing. As thepart grows, the part may benefit from support to prevent it frombreaking loose from the vertical table. To provide such support, one ormore conveyors, or support members such as support rails, may extendthrough one or more openings at the bottom of the vertical table. Theseconveyors may extend from the horizontal work table to a position at thebottom surface of the part. One or more rollers may be provided belowthis conveyor and may ride on the horizontal table for supportingsupport the weight of the part as it is manufactured. The back of thisconveyor may be mounted in a fixed position behind the machine such thata front of the conveyor is located slightly behind a position of thenozzle where printing is performed by depositing each layer of material.

For parts which do not have a flat bottom, other forms of removablesupport may be used to brace and support the part. As the part may bestationary with respect to the horizontal work table (e.g., thehorizontal work table and printed part may move together as a unit), thehorizontal work table may be provided with one or more supports such asblocks (which may include any suitable material, such as metal, wood,etc.), mechanical lifts, hydraulic jacks, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary aspects of the presentdisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIG. 1 is a perspective view of an exemplary CNC machine with a movingwork table operable to form articles via additive manufacturing,according to an aspect of the present disclosure;

FIG. 2 is a perspective view of an exemplary carrier and extruderassembly of the CNC machine shown in FIG. 1;

FIG. 3 is an enlarged perspective view of an exemplary carrier andapplicator assembly of the exemplary CNC machine shown in FIG. 1;

FIG. 4 is an enlarged perspective view of an exemplary carrier andapplicator head for vertical printing with the CNC machine shown in FIG.1;

FIG. 5 is an enlarged cross-sectional view of the exemplary applicatorhead shown in FIGS. 3 and 4;

FIG. 6 is a side view of the exemplary CNC machine and work table shownin FIG. 1; and

FIG. 7 is an enlarged side view of the indicated portion of FIG. 6.

DETAILED DESCRIPTION

The present disclosure is drawn to, among other things, methods andapparatus for fabricating multiple components via additive manufacturingor 3D printing techniques. Specifically, the methods and apparatusdescribed herein comprise a machine design which may have a lower costwhile being able to perform both print and trim operations for near netshape additive manufacturing. Moreover, the methods and apparatus mayprovide a machine which may require less space than dual gantry designs.

Referring to FIG. 1, an additive manufacturing apparatus or CNC machine1 may include a horizontal work table 27 including a horizontal surfacethat is disposed in an x-y (horizontal) plane. Horizontal work table 27,including the horizontal surface, may be movable along a set of guiderails 21, 22, and 23. Each of the guide rails 21, 22, and 23 may eachextend along an x-axis on a bed 20. A gantry 26 may extend horizontallyover work table 27. In the exemplary configuration shown in FIG. 1,gantry 26 may extend along a y-axis that is orthogonal or approximatelyorthogonal to the x-axis. Gantry 26 may extend horizontally over atleast an entire width of work table 27. Gantry 26 may be supported on apair of vertically-extending support legs 85 and 86 which are mounted tothe bed 20. The gantry may be fixed in position (e.g., the gantry doesnot include a mechanism or motor, such as a servomotor, to move thegantry in either a vertical direction, a horizontal direction, or both).If desired, a fume extraction system may be provided within one or bothof support legs 85 and 86 to remove smoke and/or fumes created duringoperation of CNC machine 1.

A pair of carriages, such as print carriage 24 and trim carriage 48, maybe supported on gantry 26. In one aspect, carriages 24 and 48 maytogether be supported on a single support member 30 mounted to anddisplaceable along one or more guide rails 31, 32, and 33. Guide rails31, 32, and 33 may be provided on the gantry 26 so as to extend alongthe y-axis. Carriages 24 and 48 may be displaceable as a unit by aservomotor 79, along a y-axis on one or more guide rails 31, 32, and 33.As shown in FIG. 1, rails 31, 32, and 33 may be mounted on the gantry 26and operatively connected to support member 30. Guide rails 31, 32, and33 may, in at least some configurations, extend longer than a width ofwork tables 27 and 37. In an alternative configuration, carriages 24 and48 may be provided with separate support members (e.g., a plurality ofsupport members 30) and separate servomotors, so as to be displaceablealong one or more guide rails 31, 32, and 33 (and the y-axis)independent of each other.

A trim carrier 50 for trim head 90 may be mounted on a set of spacedapart, vertically-extending guide rails 28, 29. Guide rails 28, 29 maybe supported on trim carriage 48 for displacement of trim carrier 50 andtrim head 90 relative to the trim carriage 48 along a vertical directionor z-axis. In a similar manner, a print carrier 25 for print head (orapplicator head) 43 may be mounted on a set of spaced apart,vertically-extending guide rails 34, 35 supported on print carriage 24for displacement of print carrier 25 relative to print carriage 24 alonga z-axis. The print and trim carriers 25 and 50 may be slidablydisplaceable with respect to the z-axis by two or more servomotorsrespectively mounted on print and trim carriages 24 and 48 andoperatively connected to print carrier 25 and trim carrier 50,respectively. Trim carrier 50 may be configured to be moved to an upwardparked location above a top edge of vertical work table 37 to avoidinterference with print carrier 25 or with a part being manufactured.For example, trim carrier 50 may be parked while the print carrier 25 isactive and moving with respect to work table 27. Similarly, printcarrier 25 may be moved upward and parked with while trim carrier 50 isoperating. In configurations where print carrier 25 and trim carrier 50are separate and movable independent with respect to the y-axis, one ofthe carriers 25, 50 may positioned or parked to the side of the tablealong the y-axis while the other of the carrier 25, 50 operates overhorizontal work table 27, thus allowing the operating carrier to movefrom side to side with respect to work table 27 without interferencefrom the other carrier.

Vertical work table 37 may be detachably mounted to a top end or surfaceof the horizontal work table 27 for vertically printing parts. Aconveyor or support member 36, such as a slide or support rail, may bedetachably mounted to an end of bed 20. In one aspect, support member 36may be provided as a plurality of rails 36 that extend along the x-axisand may be configured to roll and/or slide with respect to wear plates87 supported on top of horizontal work table 27. Wear plates 87 mayextend below vertical work table 37, as shown in FIG. 1. Vertical worktable 37 may be configured to move backward from the perspective of FIG.1 in a direction away from gantry 26 (along the x-axis) while supportmembers 36 remain at an approximately constant position underneathvertical work table 37, and with respect to gantry 26, for supportingvertically printed parts. As described below, the part may slide along asurface of one or more support members 36 during manufacturing in thismanner.

Extruder 61 (FIG. 1) may be mounted in a linearly movable manner tocarrier 25 by a set of rails 34 and 35 and bearings (not shown) on rails34 and 35. With reference to FIG. 2, extruder 61 may be driven by aservomotor 38 through a gearbox 39 which is attached to transitionhousing 37. Extruder 61 may receive thermoplastic pellets through a feedhousing 40. An extruder screw of extruder 61 may transfer thisthermoplastic material through a barrel 42 where the pellets are meltedby friction of the rotating screw and/or heat produced by heaters 41.Molten thermoplastic material may be provided by extruder 61 to positivedisplacement gear pump 62 (FIGS. 3 and 4).

As best shown in FIG. 3, positive displacement gear pump (or melt pump)62 may be fixedly mounted to the bottom of carrier 25. Gear pump 62 maybe driven by a servomotor 63 through a gearbox 64. The gear pump 62 mayreceive molten plastic material from extruder 61, as described above, inorder to meter out precise amounts of thermoplastic material atdetermined flow rates to nozzle 51 to print the part. The use of bothextruder 61 and melt pump 62 together may provide the ability to utilizeextruder screw configurations which may cause uneven flow inconfigurations where only an extruder is provided. In one aspect, themelt pump may act to even out material flow and provide increased designfreedom for the extrusion screw.

Print head or applicator head 43 may be attached below gear pump 62.Applicator head 43 may include a bead shaping roller 59 rotationallymounted in carrier bracket 47, may provide a means for flattening andleveling an oversized bead of fluid material (e.g., molten thermoplasticmaterial) extruded by the nozzle 51. Carrier bracket 47 may be adaptedto be rotationally displaced by a servomotor 60. For example, servomotor60 may be operably connected to carrier bracket 47 by a pulley orsprocket 56 and belt or chain 65. Applicator head 43 and nozzle 51 maybe used for printing horizontally e.g., on a horizontally-extendingsurface such as horizontal work table 27, as shown in FIG. 1. Whenhorizontal printing is performed, vertical work table 37, support sliderails 36, and wear plates 87 may be removed from CNC machine 1.Applicator head 43 may include a safety bumper 82 provided aroundapplicator head 43 to pause or stop operation of CNC machine 1 if anobstacle is encountered.

With reference to FIG. 4, applicator head 43 may be fixed below the gearpump 62 at a position that is angled or rotated 90° with respect toprint carrier 25, as compared to the position of applicator head 43shown in FIG. 3. Thus, the configuration of FIG. 3 may be employed forprinting on a horizontal surface (e.g., horizontal work table 27). Thisconfiguration may be referred to as a horizontal-printing configuration.The configuration illustrated in FIG. 4 may be employed for printing ona vertical surface (e.g., vertical work table 37), referred to herein asa vertical-printing configuration. In each of the horizontal-printingand vertical-printing configurations shown in FIGS. 3 and 4,respectively, applicator head 43 itself may have the same shape andcomponents. The 90° change in the position of applicator head 43 betweenthese configurations may be achieved by installing a 90° angledtransition joint 83 between gear pump 62 and nozzle 51 (see FIG. 3), asshown in FIG. 4. Additional support for applicator head 43 may beprovided by one or more 90° mount plates 84 for connecting to theapplication head 43. In the exemplary vertical-printing configurationillustrated in FIG. 4, a pair of 90° mount plates 84 may be provided onopposite sides with regards to 90° angled transition joint 83. Whenapplicator head 43 and gear pump 62 are connected to each other by 90°angled transition joint 83, applicator head 43 may be configured toprint vertically on vertical work table 37 by extending material throughhorizontally-extending nozzle 51, as shown in FIG. 1. Also, in thevertical-printing configuration, gear pump 62 may be driven by the sameservomotor 63 and gearbox 64 as the horizontal-printing configurationshown in FIG. 3.

When in the horizontal-printing configuration, the CNC machine 1 mayprint a part as tall as a height (z-axis) limit that corresponds to amaximum printing height of CNC machine 1. When in the vertical-printingconfiguration, CNC machine may print a part as long as a length (x-axis)limit that corresponds to the available horizontal work table space.

With reference to FIG. 5, applicator head 43 may include a housing 46with a rotary union mounted therein. A sprocket 56 may be machined intoan inner hub 76 of the rotary union. The inner hub 76 may have anopening with a diameter sized to receive the heated print nozzle 51. Theinner hub 76 may rotate on a set of bearings 49 provided in an outerhousing 75 of the rotary union. A compression roller assembly may beattached to the inner hub 76 of the rotary union such that compressionroller 59 rotates about the print nozzle 51. The rotary union may alsocontain barb fittings 67 and 68 in fluid communication with coolantpassages 70. In one aspect, coolant passages 70 may surround the innerhub 76 and the inside of the outer housing 75 of the rotary union.Coolant passages 70 may continue through quick disconnect fittings 72into the axle 73 of the compression roller 59. Applicator head 43 may beusable in both the horizontal-printing configuration thevertical-printing configuration (by attaching 90° angled transitionjoint 83 and optionally one or more 90° mount plates 84).

As shown in FIGS. 3-5, an oversized molten bead of a flowable material(e.g., molten thermoplastic) may be provided under pressure from asource disposed on carrier 25 (e.g. gear pump 62) or another source, toapplicator head 43. This material may be provided to nozzle 51 incommunication with applicator head 43, which may be fixedly connected tocarrier 25. In use, the flowable material 53 (e.g., thermoplasticmaterial) may be heated sufficiently to form a large molten bead, whichis then extruded through applicator nozzle 51 to form substantiallyuniform, smooth rows of deposited material on work tables 27, 37 in aseries of layers. Such beads of molten material may be flattened,leveled, and/or fused to adjoining layers with substantially no trappedair by bead-shaping compression roller 59 with the layers forming 3Dprinted products.

FIG. 6 is a side view of CNC machine 1 with the gantry support leg 85omitted for clarity. The detachable vertical work table 37 may beattached and used in conjunction with the vertical-printingconfiguration for applicator head 43 to allow CNC machine 1 may toproduce relatively long parts without increasing the height of themachine. Vertical work table 37 may be mounted directly to a top end ofthe movable horizontal work table 27. One or more detachable supportmembers 36, such as rails, may be fixed underneath vertical work table37 to support the vertically-printed part. Support member 36 may slideor roll (e.g., by rollers) with respect to wear plates 87 fixed (e.g.,by bolts) to horizontal work table 27. For example, once a layer ofthermoplastic material is deposited in one or more rows on vertical worktable 37, the horizontal and vertical work tables 27, 37 may move as aunit away from applicator head 43. During this motion, horizontal worktable 27, may slide along a roller of support member 36. As the rollerrotates due to the motion of work table 27, the roller and supportmember 36 may remain in an approximately constant position. Thus, as thelayers of the part are deposited, support members 36 may create a shelfsurface that applicator head 43 can print against and that may providesupport to the part.

While the vertical work table 37 moves away from applicator head 43, thedetachable support members 36 may advance through an opening at thebottom of vertical work table 37 due to the motion of vertical worktable 37. The part may be supported with respect to gravity by supportmember 36. Moreover, the part may slide across the upper surface ofsupport member 36 while remaining secured to vertical work table 37. Asdescribed above, vertical work table 37, support members 36, and wearplates 87 may be removable, thereafter allowing CNC machine 1 to printon an entire top surface of the horizontal work table 27 with applicatorhead 43 in the horizontal-printing configuration.

FIG. 7 is an enlarged view of the section of FIG. 6 within the adashed-line box. Thermoplastic material 53 may be horizontally extrudedfrom applicator head 43 through nozzle 51 (which is behind compressionroller 59 from the perspective of FIG. 7) onto a surface of verticalwork table 37. In one configuration, this vertical surface may beprovided on a pellet or bead board 80 secured to a base board 81.Compression roller 59 may be configured to compress and flatten bead 53against pellet board 80. Pellet board 80 and base board 81 may togetherbe removably fastened to vertical work table 37. After the first layerof thermoplastic material is deposited on a side surface of pellet board80 and before nozzle 51 begins deposition of the next layer, verticalwork table 37 may be drawn or moved in a direction away from applicatorhead 43, as described above. In one aspect, the distance of thismovement of vertical work table 37 may be approximately equal to thethickness of one layer of a bead of thermoplastic material 53. One ormore additional layers may be deposited on the first layer. After thedeposition of each layer, the above-described movement may be repeated.In one aspect, this movement may be performed by a servomotor andgearbox that are controlled with the use of feedback from one or moreencoders. As vertical work table 37 is drawn away from applicator headby the distance of one layer of material 53, support member 36 mayremain in place, allowing the part to slide along a support surfaceformed at the top of each support member 36.

This process may be repeated until the part, which may have a lengthequal to the length of the horizontal work table 27, is complete. Asvertical work table 37 moves away from applicator head 43 in alayer-by-layer manner, a length of the part may grow and the part mayslide layer-by-layer, along the surface of support member 36. Thus, abottom surface of the growing part may be slidably supported on supportmember or rail 36. Any of the layers may be supported on support member36, including the first layer or one or more additional layers. In anexemplary configuration, once the part reaches a sufficient length dueto the deposition of a plurality of layers, the part may extend downwardby a distance sufficient to reach support member 36. Thus, supportmember 36 may prevent undesired separation of the part from verticalwork table 37 and/or pellet board 80.

From the foregoing detailed description, it will be evident that thereare a number of changes, adaptations and modifications of the presentinvention which come within the province of those persons havingordinary skill in the art to which the aforementioned inventionpertains. However, it is intended that all such variations not departingfrom the spirit of the invention be considered as within the scopethereof as limited by the appended claims.

1.-32. (canceled)
 33. An additive manufacturing method, comprising:supporting an applicator on a fixed support structure; depositing afirst layer of thermoplastic material on a surface with the applicatorand while moving the applicator in a first horizontal direction; movingthe surface with the deposited thermoplastic material in a secondhorizontal direction; and depositing one or more additional layers ofthermoplastic material on the first layer of thermoplastic material. 34.The additive manufacturing method of claim 33, wherein the firsthorizontal direction is orthogonal to the second horizontal direction.35. The additive manufacturing method of claim 33, wherein theapplicator is supported by the fixed support structure, a firstvertically-extending support, and a second vertically-extending support.36. The additive manufacturing method of claim 33, wherein depositingthe first layer of thermoplastic material is performed by extruding thethermoplastic material via a nozzle.
 37. The additive manufacturingmethod of claim 33, wherein moving the surface includes translating awork table with respect to a structure that supports the work table. 38.The additive manufacturing method of claim 37, wherein the work tabletranslates by sliding along a plurality of rollers.
 39. The additivemanufacturing method of claim 38, wherein the fixed support structureextends above the work table.
 40. The additive manufacturing method ofclaim 39, further including moving the applicator in a verticaldirection while the support structure remains fixed.
 41. The additivemanufacturing method of claim 33, further including trimming a part thatincludes the first layer and the one or more additional layers with atrim head supported on support structure with the applicator.
 42. Anadditive manufacturing method, comprising: supporting an applicator on asupport structure fixedly secured to a first vertically-extendingsupport and a second vertically-extending support, the support structureextending across the first vertically-extending support and the secondvertically-extending support; depositing a first layer of thermoplasticmaterial on a surface positioned below the support structure with theapplicator, while moving the applicator in a first horizontal direction;moving the surface in a second direction perpendicular to the firsthorizontal direction; and depositing one or more additional layers ofthermoplastic material on the first layer of thermoplastic material. 43.The additive manufacturing method of claim 42, wherein the thermoplasticmaterial is deposited from a nozzle in communication with an extrudersecured to the support structure.
 44. The additive manufacturing methodof claim 43, further including moving the extruder in the firsthorizontal direction with the applicator.
 45. The additive manufacturingmethod of claim 42, further including trimming a part that includes thefirst layer and the one or more additional layers with a trim headsupported on the support structure with the applicator.
 46. An additivemanufacturing method, comprising: supporting an applicator on a supportmember fixedly secured to a first vertically-extending support and asecond vertically-extending support, the support member extending acrossthe first vertically-extending support and the secondvertically-extending support; depositing a first layer of thermoplasticmaterial on a surface positioned below the support member with a nozzleof the applicator and while moving the applicator in a first horizontaldirection; depositing one or more additional layers of thermoplasticmaterial on the first layer of thermoplastic material; and trimming apart that formed by the first layer and the one or more additionallayers.
 47. The additive manufacturing method of claim 46, wherein thesurface is a surface of a moveable work table.
 48. The additivemanufacturing method of claim 46, wherein the applicator is supported ona print carrier slidably connected to the support member.
 49. Theadditive manufacturing method of claim 48, wherein the applicator issupported on a print carrier and the trimming is performed by use of atrim carrier secured to the print carrier by a linking member.
 50. Theadditive manufacturing method of claim 46, wherein the support memberextends across at least an entire width of a work table that includesthe surface.
 51. The additive manufacturing method of claim 50, whereinthe applicator is supported on a print carrier slidably secured on arail of the support member that extends longer than a width of the worktable.
 52. The additive manufacturing method of claim 50, wherein thework table includes a vertically-extending surface, thevertically-extending surface being movable in a direction away from theapplicator during operation of the applicator or when trimming.